1. Field of the Invention
The present invention relates in general to mechanical slides and slideways and relates in particular to such apparatus having an adjustable sliding resistance to provide a high quality feel as an operator manually drives the slide along the slideway.
2. Description of Prior Developments
Precision positioning instruments such as micromanipulators and stereotaxic devices are used to conduct laboratory procedures on test specimens such as laboratory animals, eg, rats and mice. Hypodermic needles, electrodes, probes and other tools are carefully applied to a test specimen by an operator such as described in co-pending patent application titled xe2x80x9cManual Drive for Positioning Precision instrumentsxe2x80x9d having serial number 09/707,051, filed on Nov. 6, 2000 by the present inventor and incorporated herein by reference.
In order to provide a high quality precision sliding movement between a slide on which a precision laboratory tool is mounted, and a slideway mounted on the positioning instrument, prior designs have used ball bearings and linear bearings to support the slide on the slideway. Although these bearings achieve the desired result, they significantly increase the cost and complexity of the slide assembly.
Some positioning instruments use dovetail connections between a slide and slideway. However, such connections typically require periodic lubrication with oil or grease to overcome the inherent high friction associated with dovetail slides.
Accordingly, a need exists for a high quality, precision slide and slideway assembly which has a relatively simple construction and is economical to produce.
A further need exists for such a slide and slideway assembly which avoids the use of expensive ball bearings and linear bearings.
Yet a further need exists for such an assembly which avoids the use of dovetail joints and eliminates the need for lubrication with oil or grease.
Still a further need exists for an inexpensive precision slide and slideway assembly which produces a smooth precision feel or xe2x80x9ctightxe2x80x9d feel to an operator as the operator manually drives the slide over the slideway.
Still a further need exists for such an assembly which can be easily adjusted to select the amount of friction and play between the slide and slideway so as to optimize the xe2x80x9cfeelxe2x80x9d of the slide assembly as perceived by an operator.
The present invention has been developed to fulfill the needs noted above and therefore has as an object the provision of an economical slide and slideway assembly that has a simple construction yet which has a tight precision feel to an operator during operation of the assembly.
A further object of the invention is the provision of a slide and slideway assembly which does not require periodic lubrication with oil or grease.
Another object of the invention is the provision of a precision slide and slideway assembly which does not require the use of ball bearings such as linear ball bearings and which avoids the use of dovetail interconnections.
Yet another object of the invention is the provision of a precision slide and slideway assembly which has an adjustable sliding friction fit between the slide and slideway to optimize the feel perceived by an operator of the slide as it moves over the slideway. A smooth but tight or play-free interfit can be achieved with such an adjustment.
These and other objects are met in accordance with the present invention which is directed to a precision slide and slideway assembly having a simple construction which obviates the need for ball bearings such as linear ball bearings, and avoids the use of oil or grease lubricated dovetail interconnections. The amount of sliding friction produced between the slide and slideway can be adjusted, selected and controlled by a simple adjustment which biases a tongue against a groove of a tongue and groove interconnection between the slide and slideway.
The tongue is mounted or formed on a cantilevered spring arm which can be flexed toward and away from the groove. The greater the elastic deformation and flexure of the free end of the spring arm toward the groove, the greater is the sliding friction produced between the tongue and groove, and vice versa.
A strip of ultra high molecular weight plastic tape can be positioned between the tongue and groove to reduce sliding friction and produce a smooth, xe2x80x9csilkyxe2x80x9d yet tight precision feel when an operator manually turns the drive knobs which drive the slide over the slideway. Although the slide and slideway assembly has a minimum of parts and is economical to manufacture, it has the tight precision fit, feel and stability of similar systems costing much more due to their increased complexity.
The aforementioned objects, features and advantages of the invention will, in part, be pointed out with particularity, and will, in part, become obvious from the following more detailed description of the invention, taken in conjunction with the accompanying drawings, which form an integral part thereof.